var WebRtcStreamer = (function() {

	/**
	 * Interface with WebRTC-streamer API
	 * @constructor
	 * @param {string} videoElement - id of the video element tag
	 * @param {string} srvurl -  url of webrtc-streamer (default is current location)
	*/
	var WebRtcStreamer = function WebRtcStreamer (videoElement, srvurl) {
		if (typeof videoElement === "string") {
			this.videoElement = document.getElementById(videoElement);
		} else {
			this.videoElement = videoElement;
		}
		this.srvurl           = srvurl || location.protocol+"//"+window.location.hostname+":"+window.location.port;
		this.pc               = null;
	
		this.mediaConstraints = { offerToReceiveAudio: true, offerToReceiveVideo: true };
	
		this.iceServers = null;
		this.earlyCandidates = [];
	}
	
	WebRtcStreamer.prototype._handleHttpErrors = function (response) {
		if (!response.ok) {
			throw Error(response.statusText);
		}
		return response;
	}
	
	/**
	 * Connect a WebRTC Stream to videoElement
	 * @param {string} videourl - id of WebRTC video stream
	 * @param {string} audiourl - id of WebRTC audio stream
	 * @param {string} options -  options of WebRTC call
	 * @param {string} stream  -  local stream to send
	*/
	WebRtcStreamer.prototype.connect = function(videourl, audiourl, options, localstream) {
		this.disconnect();
	
		// getIceServers is not already received
		if (!this.iceServers) {
			console.log("Get IceServers");
	
			fetch(this.srvurl + "/api/getIceServers")
				.then(this._handleHttpErrors)
				.then( (response) => (response.json()) )
				.then( (response) =>  this.onReceiveGetIceServers(response, videourl, audiourl, options, localstream))
				.catch( (error) => this.onError("getIceServers " + error ))
	
		} else {
			this.onReceiveGetIceServers(this.iceServers, videourl, audiourl, options, localstream);
		}
	}
	
	/**
	 * Disconnect a WebRTC Stream and clear videoElement source
	*/
	WebRtcStreamer.prototype.disconnect = function() {
		if (this.videoElement?.srcObject) {
			this.videoElement.srcObject.getTracks().forEach(track => {
				track.stop()
				this.videoElement.srcObject.removeTrack(track);
			});
		}
		if (this.pc) {
			fetch(this.srvurl + "/api/hangup?peerid=" + this.pc.peerid)
				.then(this._handleHttpErrors)
				.catch( (error) => this.onError("hangup " + error ))
	
	
			try {
				this.pc.close();
			}
			catch (e) {
				console.log ("Failure close peer connection:" + e);
			}
			this.pc = null;
		}
	}
	
	/*
	* GetIceServers callback
	*/
	WebRtcStreamer.prototype.onReceiveGetIceServers = function(iceServers, videourl, audiourl, options, stream) {
		this.iceServers       = iceServers;
		this.pcConfig         = iceServers || {"iceServers": [] };
		try {
			this.createPeerConnection();
	
			var callurl = this.srvurl + "/api/call?peerid=" + this.pc.peerid + "&url=" + encodeURIComponent(videourl);
			if (audiourl) {
				callurl += "&audiourl="+encodeURIComponent(audiourl);
			}
			if (options) {
				callurl += "&options="+encodeURIComponent(options);
			}
	
			if (stream) {
				this.pc.addStream(stream);
			}
	
					// clear early candidates
			this.earlyCandidates.length = 0;
	
			// create Offer
			this.pc.createOffer(this.mediaConstraints).then((sessionDescription) => {
				//console.log("Create offer:" + JSON.stringify(sessionDescription));
	
				this.pc.setLocalDescription(sessionDescription)
					.then(() => {
						fetch(callurl, { method: "POST", body: JSON.stringify(sessionDescription) })
							.then(this._handleHttpErrors)
							.then( (response) => (response.json()) )
							.catch( (error) => this.onError("call " + error ))
							.then( (response) =>  this.onReceiveCall(response) )
							.catch( (error) => this.onError("call " + error ))
	
					}, (error) => {
						console.log ("setLocalDescription error:" + JSON.stringify(error));
					});
	
			}, (error) => {
				alert("Create offer error:" + JSON.stringify(error));
			});
	
		} catch (e) {
			this.disconnect();
			alert("connect error: " + e);
		}
	}
	
	
	WebRtcStreamer.prototype.getIceCandidate = function() {
		fetch(this.srvurl + "/api/getIceCandidate?peerid=" + this.pc.peerid)
			.then(this._handleHttpErrors)
			.then( (response) => (response.json()) )
			.then( (response) =>  this.onReceiveCandidate(response))
			.catch( (error) => this.onError("getIceCandidate " + error ))
	}
	
	/*
	* create RTCPeerConnection
	*/
	WebRtcStreamer.prototype.createPeerConnection = function() {
		console.log("createPeerConnection  config: " + JSON.stringify(this.pcConfig));
		this.pc = new RTCPeerConnection(this.pcConfig);
		var pc = this.pc;
		pc.peerid = Math.random();
	
		pc.onicecandidate = (evt) => this.onIceCandidate(evt);
		pc.onaddstream    = (evt) => this.onAddStream(evt);
		pc.oniceconnectionstatechange = (evt) => {
			console.log("oniceconnectionstatechange  state: " + pc.iceConnectionState);
			if (this.videoElement) {
				if (pc.iceConnectionState === "connected") {
					this.videoElement.style.opacity = "1.0";
				}
				else if (pc.iceConnectionState === "disconnected") {
					this.videoElement.style.opacity = "0.25";
				}
				else if ( (pc.iceConnectionState === "failed") || (pc.iceConnectionState === "closed") )  {
					this.videoElement.style.opacity = "0.5";
				} else if (pc.iceConnectionState === "new") {
					this.getIceCandidate();
				}
			}
		}
		pc.ondatachannel = function(evt) {
			console.log("remote datachannel created:"+JSON.stringify(evt));
	
			evt.channel.onopen = function () {
				console.log("remote datachannel open");
				this.send("remote channel openned");
			}
			evt.channel.onmessage = function (event) {
				console.log("remote datachannel recv:"+JSON.stringify(event.data));
			}
		}
		pc.onicegatheringstatechange = function() {
			if (pc.iceGatheringState === "complete") {
				const recvs = pc.getReceivers();
	
				recvs.forEach((recv) => {
				  if (recv.track && recv.track.kind === "video") {
					console.log("codecs:" + JSON.stringify(recv.getParameters().codecs))
				  }
				});
			  }
		}
	
		try {
			var dataChannel = pc.createDataChannel("ClientDataChannel");
			dataChannel.onopen = function() {
				console.log("local datachannel open");
				this.send("local channel openned");
			}
			dataChannel.onmessage = function(evt) {
				console.log("local datachannel recv:"+JSON.stringify(evt.data));
			}
		} catch (e) {
			console.log("Cannor create datachannel error: " + e);
		}
	
		console.log("Created RTCPeerConnnection with config: " + JSON.stringify(this.pcConfig) );
		return pc;
	}
	
	
	/*
	* RTCPeerConnection IceCandidate callback
	*/
	WebRtcStreamer.prototype.onIceCandidate = function (event) {
		if (event.candidate) {
			if (this.pc.currentRemoteDescription)  {
				this.addIceCandidate(this.pc.peerid, event.candidate);
			} else {
				this.earlyCandidates.push(event.candidate);
			}
		}
		else {
			console.log("End of candidates.");
		}
	}
	
	
	WebRtcStreamer.prototype.addIceCandidate = function(peerid, candidate) {
		fetch(this.srvurl + "/api/addIceCandidate?peerid="+peerid, { method: "POST", body: JSON.stringify(candidate) })
			.then(this._handleHttpErrors)
			.then( (response) => (response.json()) )
			.then( (response) =>  {console.log("addIceCandidate ok:" + response)})
			.catch( (error) => this.onError("addIceCandidate " + error ))
	}
	
	/*
	* RTCPeerConnection AddTrack callback
	*/
	WebRtcStreamer.prototype.onAddStream = function(event) {
		console.log("Remote track added:" +  JSON.stringify(event));
	
		this.videoElement.srcObject = event.stream;
		var promise = this.videoElement.play();
		if (promise !== undefined) {
		  promise.catch((error) => {
			console.warn("error:"+error);
			this.videoElement.setAttribute("controls", true);
		  });
		}
	}
	
	/*
	* AJAX /call callback
	*/
	WebRtcStreamer.prototype.onReceiveCall = function(dataJson) {
	
		console.log("offer: " + JSON.stringify(dataJson));
		var descr = new RTCSessionDescription(dataJson);
		this.pc.setRemoteDescription(descr).then(() =>  {
				console.log ("setRemoteDescription ok");
				while (this.earlyCandidates.length) {
					var candidate = this.earlyCandidates.shift();
					this.addIceCandidate(this.pc.peerid, candidate);
				}
	
				this.getIceCandidate()
			}
			, (error) => {
				console.log ("setRemoteDescription error:" + JSON.stringify(error));
			});
	}
	
	/*
	* AJAX /getIceCandidate callback
	*/
	WebRtcStreamer.prototype.onReceiveCandidate = function(dataJson) {
		console.log("candidate: " + JSON.stringify(dataJson));
		if (dataJson) {
			for (var i=0; i<dataJson.length; i++) {
				var candidate = new RTCIceCandidate(dataJson[i]);
	
				console.log("Adding ICE candidate :" + JSON.stringify(candidate) );
				this.pc.addIceCandidate(candidate).then( () =>      { console.log ("addIceCandidate OK"); }
					, (error) => { console.log ("addIceCandidate error:" + JSON.stringify(error)); } );
			}
			this.pc.addIceCandidate();
		}
	}
	
	
	/*
	* AJAX callback for Error
	*/
	WebRtcStreamer.prototype.onError = function(status) {
		console.log("onError:" + status);
	}
	
	return WebRtcStreamer;
	})();
	
	if (typeof window !== 'undefined' && typeof window.document !== 'undefined') {
		window.WebRtcStreamer = WebRtcStreamer;
	}
	if (typeof module !== 'undefined' && typeof module.exports !== 'undefined') {
		module.exports = WebRtcStreamer;
	}
	